21021212101993 has 2 divisors, whose sum is σ = 21021212101994. Its totient is φ = 21021212101992.

The previous prime is 21021212101951. The next prime is 21021212102057. The reversal of 21021212101993 is 39910121212012.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11914626387049 + 9106585714944 = 3451757^2 + 3017712^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021212101993 - 2³³ = 21012622167401 is a prime.

It is a super-2 number, since 2×21021212101993² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21021212101913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510606050996 + 10510606050997.

It is an arithmetic number, because the mean of its divisors is an integer number (10510606050997).

Almost surely, 2^{21021212101993} is an apocalyptic number.

It is an amenable number.

21021212101993 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021212101993 is an equidigital number, since it uses as much as digits as its factorization.

21021212101993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3888, while the sum is 34.

The spelling of 21021212101993 in words is "twenty-one trillion, twenty-one billion, two hundred twelve million, one hundred one thousand, nine hundred ninety-three".